Tech Tuesday: DH Helmet vs. Motocross Helmet: Which is Safer?

This Tech Tuesday, Pinkbike features a think-piece by Guest-Contributor Robert Beaupre, who pits conventional helmet logic against new information that challenges existing standards and postulates that a cycling-friendly helmet design which utilizes a more flexible shell better-protects the rider in comparison to sturdier Motocross lids that must pass more stringent tests. Many DH and park riders use Motocross helmets in the assumption that they offer more protection. Beaupre's essay gives much reason to doubt that logic. To enlist industry input, we contacted two helmet makers: Bell Sports and Kali Protectives. Bell Sports did not choose to participate. It's a good read. -RC

Moto VS DH - Which Helmet is Safer for Cycling?

Among many gravity riders, there is a common assumption that Motocross helmets are safer than full-face bicycle helmets. On the surface, that seems like a sensible notion: Motocross helmets are larger and heavier than mountain bike lids, and having more material between your head and the ground in a crash is a good thing, right?

Downhill helmets and Motocross helmets may look similar, but there is a key difference between them.

Unfortunately, it may not be that simple. There is an ongoing debate in the motorcycle industry about how stiff a helmet should be to offer maximum protection. A number of critics have suggested that many motorcycle helmets, particularly those made to meet the demanding SNELL certification standard, are engineered to be so rigid that they actually offer less protection in the most common types of crashes. What does this mean to you as a mountain biker? If you choose to wear a Motocross helmet instead of a bicycle helmet when you ride downhill, it could mean a lot.

Which Test is Best?

To understand why the motorcycle helmet debate matters to bicycle riders, you have to understand the testing demands that these helmets are engineered to meet. Common testing procedures for motorcycle helmets seek to simulate the crashes that a rider could encounter on the road. The tests at helmet labs routinely drop helmets onto differently shaped objects from considerable heights. These intense impacts make sense considering the energy levels involved when a motorcyclist's head strikes the ground (or another vehicle) at highway speeds.

The testing used by the SNELL Memorial Foundation, a non-profit group that has certified motorcycle helmets for decades, involves even greater stresses than the standard Department of Transportation (DOT) testing that a helmet must pass to be sold in the U.S. The latest SNELL certification standard (M2010) requires that a helmet transmit less than 275 g-forces to the headform inside of the helmet in any part of the testing - a process that involves some very severe impacts.

According to critics, trouble arises from the substantial stiffness that motorcycle helmets must employ to manage these very severe impacts in the SNELL testing. In a sense, the energy absorbing EPS foam inside a helmet works the same way as the suspension on a mountain bike. Just as the suspension on your bike absorbs the energy and slows the impacts from bumps and drops, a helmet is made to absorb the energy that your head encounters in a crash.

In most crashes, the helmet's primary job is to slow your head down so it doesn't take the full force of the impact. It's the EPS foam inside of the helmet, rather than the helmet's outer shell, that handles most of this task. The foam is designed to compress upon impact, slowing your head as it does so. But if the foam fails to slow your head sufficiently, your brain will smack into the inside of your skull, causing a concussion. And if the helmet really fails at this task, the consequences are usually grim. The problem with a very stiff helmet liner - one engineered to withstand the brutal impacts a motorcyclist on the street could encounter - is the same problem you'd find with a downhill bike that's been set up specifically to withstand ten-foot drops to flat. The helmet with its super-stiff liner won't be compliant enough to cushion smaller impacts, just as the downhill bike with super-stiff suspension won't effectively cushion small and medium-sized hits.

Kali's Prana Downhill helmet passes the US DOT and the European ECE 22.05 helmet standards, but does not pass the SNELL standards. Recent information indicates that this may be a good thing. Ian Hylands photo

When it comes to brain trauma, small and medium-sized hits matter. Neurologists have learned many new things about the effects of concussions in recent years, and the news usually isn't good for those who've suffered them. Repeated blows to the head have been correlated with chronic traumatic encephalopathy (CTE), a brain condition linked to the deaths of some retired NFL players. All of this has led researchers to suspect that concussions may be much more dangerous than previously imagined.

Critics also point to the fact that it doesn't take multiple concussions to change a person's life. Even a single concussion can cause problems with cognition and memory that can last indefinitely. James Newman, a former director of the SNELL Foundation, has estimated that impacts of 200 g's or more - 75 g's less than the figures required for Snell M2010 certification - typically correspond to severe brain injuries or worse.

Alex Mancini Supermans into a rock garden at Contermanskloof, South Africa - probably happy that his helmet is certified to withstand a sharp impacts. Steven Morrow photo

Experts square off

So are the motorcycle helmets being made to SNELL standards too stiff? According to a 2005 article by Motorcyclist magazine, DOT helmets outperformed their SNELL counterparts in independent tests that were designed to simulate slow- to medium-speed crashes. This wasn't especially surprising, though, since DOT helmets aren't typically engineered to be stout enough to meet SNELL standards, which means they theoretically should be more compliant in small crashes.

What was surprising was that the DOT helmets also transmitted fewer g's than the SNELL-certified helmets in the highest-energy impacts as well, raising the question of whether SNELL testing had truly become too rigorous for its own good. Ironically, the best performer in the 32-helmet Motorcyclist test was a $79.95 DOT-certified helmet, which transmitted as much as 67 g's less in violent impacts than a $400 SNELL lid.

After publication of the article, SNELL issued a rebuttal that questioned Motorcyclist's testing methods (although since then, SNELL has moved toward requiring more compliant liners in its testing -- one of the chief points of the Motorcyclist article). But the rebuttal didn't stop the controversy from growing. The debate reached a boiling point in 2009 when Dexter Ford, the author of the 2005 Motorcyclist article, wrote a story on the issue for the New York Times. Shortly after that article ran, Motorcyclist fired Ford, a veteran of three decades with the magazine, allegedly due to boycott threats from helmet manufacturers. The 2005 story no longer appears on the Motorcyclist website.

Kali Protectives Founder Brad Waldron at work with one of his full-face DH helmets. Ian Hylands photo

Talking Helmets With Kali's Brad Waldron

Brad Waldron, a long-time helmet designer and a product-testing fanatic, agrees that a more compliant shell offers more protection for lower-speed impacts typically seen in DH and Park riding. We asked Brad to comment on the differences between Moto and Downhill helmets, and the possible benefits of less-rigid shell construction. -RC

Yes, on average DH helmets are more flexible. One of the biggest reasons for this is that the DOT test for MX helmets requires a penetration test that forces the use of a stiffer shell. The test basically drives a pointed anvil directly through the shell.

SNELL believes that having a more rigid shell saves lives at the highest end of the crash spectrum, while sacrificing concussions on the lower end. I just had this discussion at the Indy motorcycle show with SNELL. I think there are arguments to this as well, but arguing the benefits of SNELL is not where I am looking to go in this discussion.

Rigid shells are worse at low-speed impacts. I believe that you want the shell to deform as soon as reasonably possible. Remember, a body in motion stays in motion until acted upon by a force. If your head hits a hard shell, your brain will continue in motion until it hits the other side of your skull. If on the other hand, the shell starts to break down and the foam is soft enough, then the dissipation of energy is starting quicker and your brain moves slower. Slowing down your brain moving inside your head is a good thing.

Our technology is to in-mold the foam with full-shell helmets, we found that when we in-molded, but did not change the stiffness of the shell, that we saw little benefits. When we made the shell much less stiff, we lowered g-forces 20-percent and more. So I am a big fan of less-stiff shells. There are limits though. You have to balance and tune the shell's stiffness to make sure it is not too soft. This kind of testing takes much time and energy. Not everyone is willing to put in an effort of such magnitude.

Making the choice

All of these facts raise a number of concerns for mountain bikers who choose motocross lids. If it's true that some top-of-the-line motorcycle helmets may be too stiff for even highway motorcycle use, what does that mean to riders who use them for downhill, where the speeds are typically much slower? Are downhill riders better off choosing helmets that were engineered for the crashes they'll likely face on a downhill course, rather than those engineered for 75-mph trips into car barriers?

While that choice remains up to you as a rider, it's clear that there are some good reasons to think twice before opting for a motocross helmet over one engineered for bicycles. This is particularly true since ASTM F1952 - a downhill-specific helmet safety certification - now appears on many bicycle helmets, giving gravity riders a discipline-specific standard of their own. Regardless of where the controversy over helmets ends, choosing the right helmet for your type of riding deserves your attention - at least to the extent you value your head.

226 Comments

Yeah but I don't have the spare money to buy a DH lid when I have MX full face already, with no clear explanation (Until now), I figured a MX helmet should do the trick; if it can handle a crash on a MX, DH should be fine. Or else is was my half shell.

Now I know I need to spend the extra money to get a DH specific one, which I will do.

I think the problem may not be in co-opting an MX helmet to DH, because people reasonably argue that the speeds and crashes may not be that different. I think the mistake is farther upstream, with the moto helmets being held to _street_ motorcycle helmet standards. Street speeds, street materials (curb, asphalt), DOT=department of transportation, remember?. If moto helmets had been allowed to be engineered and safety certified along a totally independent path from street helmets, would you not expect them to be really close to what our new breed of DH specific helmets have come to be? I don't worry at all about the safety of my ASTM1952 Fox Rampage for DH--I think this whole debate raises concern that my DOT/Snell Shoei is not as safe for moto as it could be.

have they ever experimented with something that would suspend your head inside the helmet? like a strong webbing? then have some lighter foam and a thick-ish shell? that way the helmet would be insanely lightweight and you wouldnt have to worry about what speed you were crashing a bike

the biggest pull factor for moto helmets in my opinion is the fact that if you have a large crash (on a mountainbike) then you dont necessary have to replace it. They say when you have a stack on a mtb helmet you should replace it because once the foam is compressed thats it, since a moto helmet is designed for larger hits you don't have to worry about replacing it everytime you mess up. Which in the long run costs you less over time. Everyone over here runs moto helmets for DH and that really seems to be the biggest reason as to why. Constantly replacing MTB helmets is just to expencive.

I wear a moto helmet because, just like a boxer, I love the feeling of a good knocking on the noggin. I don't do drugs, simply because this will always suffice. Do you wonder why Mike Tyson has that lisp? He's just mega high, all the time. His world is boxing. His mind is stuck on that feeling of having his brain go "swoosh, klonk, swoosh, klonk..."

Really what Kali and the other helmet manufactures should be working on is padding the inside of our skulls. I mean, thats where the damage is done! If we just enlarged our skull, thickened up the brain soup surrounding the brain (plain flour and butter, equal quantities) and added some soft fat tissue to the inside, problem solved!

I'd just like to butt in with this - if sponsors are pressuring riders to wear equipment that is potentially unsafe in a crash, is it really worth sticking with that sponsor? If I was a sponsored rider, I'd rather wear a proper lid than let a sponsor make me wear a moto lid. I think it's fairly obvious that DH lids are safer for DH, as they're designed for lower speed impacts. Face it, if people needed moto strength lids, then DH lids would be designed that way.

There is an argument for wearing a stiffer helmet if you spend a lot of time in jagged rock gardens which (at the speeds pros ride) could have a sharp impact, splitting a softer helmet. However, for the majority of us, a bike helmet is going to be a much better option for 95% of the trails we ride.It is also worth noting that a lot of the latest research indicates neck trauma may be the primary cause of concussion. The theory is that your brain detects the impact in your neck, and forces your body to go limp because a limp body sustains less overall injury than a stiff one (that's why drunken falls often result in less serious injury than the same fall by a sober person). From what I have read the jury is still out on whether neck braces help with concussion (they do help in other ways), but it is worth thinking about.

You know what's REALLY expensive? Being a vegetable with limited brain function cause you smacked your head up cause you were too cheap to replace a helmet. Moto helmets aren't made to withstand multiple crashes either.

The problem for me though is that I destroy DH helmets, i've got a DOT approved MX helmet, and notice in the article they were saying thats better than Snell. I think i'll continue to ride with it until it breaks. Also I'd like to see a comparison between the Leatt and an EVS moto brace, which is what i wear cuz it was cheaper and dissipates energy better than the leatt....

I know I know I know, trust me I know this, and trust me, if I replaced my helmet every time I crashed, i'd have an effing pile of helmets!! I crash alot, i'm recovering from one right now.... Also i haven't been paid much in the last 4 months (got a job, helping a startup, its just not up and running yet, i'm happy when i can pay my rent and have a little gas money left over). As soon as i start getting paid though i'm goin back to a DH helmet, tired of my heavy MX helmet.... But you know what, my bike is screwed right now anyways, so i can't ride until i get back into the job, so you shouldn't worry now i can only hurt myself riding urban... Haha

Typical corporate response by firing Ford after the article. He was just pointing out some flaws or oversights in how modern helmets are manufactured, then the helmet manufacturers threaten to boycott the magazine because of the article.
An intelligent response would be for the helmet manufacturer to re evaluate their products and see if Fords findings were in fact true before ignoring his research, then maybe change the manufacturing process to offer everyone a safer helmet. Instead they back out of funding the magazine insisting that the safety of their helmets are fine. Childish.
Whether the helmet manufacturers realize it or not, it is also in their best interest to produce a safer helmet too. After all someone could sue them if the helmet worn in a crash actually caused more harm than it could have prevented.

My dad told me the same thing! So i wear a 500 troy lee designs se3 helmet. thought it was the best thing till now, gonna have to upgrade to a DH specific helmet. I looked for a billion dollar helmet but they didn't make one haha!

haha yea but truthfully i would never buy a TLD moto helmet because you are only paying for the paint job. And moto helmets aren't necessarily worse, its more so the SNELL approved ones not the DOT ones. And if you ride fast than it is better for you.

Agreed. But keep in mind, buy a dh helmet that meets the ASTM F1952 standards or DOT. Three years ago I was rocking a Fox fullface at the Claymore Challenge, crashed on a jump, slammed my head, and suffered short/long term memory loss and a small brain hemorage. Took about a year to start to feel normal again. Its a fine line between to much protection and too little.

I wonder how many riders base there purchase of a helmet based on price? A new TLD D3 cost $450.00 while a motocross helmet cost roughly the same which may lead people to think "Thats alot of money for a bicycle helmet I'll just buy a motocross helmet it has to be better" type of thinking.

The D3 is steps above other helmets in weight, fit and safety. I have wrecked in dot/snell helmets and have been worse off then a wreck in my first D3. Both crashes similar impact. Plus the dot/snell helmets are much hotter and heavier causing fatigue faster.

Not true todays MX lids are between 900g-1300g and has improved ventilation for way better air flow then in the past,D3 steps above weight and safety over the other dh helmets is halv true since the new specialized deviant helmet offers more features than a D3 and is in general a lighter helmet than the D3.

This article made me want to hit things. It is inaccurate and misleading. There is no place in this discussion for any sort of reference to Road Motorcycle accidents or helmets. There are significant differences between road and off-road motorcycle construction and design. As for standards like Snell and DOT; Snell is irrelevant as it relates to car accidents and should never have been employed for bike accidents of any kind. And DOT; similar testing is used for the mandatory Aus/NZ safety standards and it does not guarantee a safe helmet. Don't underestimate motorcycle helmet designers understanding of the importance of shock absorption. Many helmet manufacturers do not bother with either the DOT or Snell standards. I would still take a quality MX helmet over a poor DH full face any day. This article only captures a small (and poorly presented) fragment of the whole picture.

Just want to add my experience and reason for sticking with a Moto/DOT helmet. Having only used 661 helmets variying from dh to moto. I can attest the only time I have never gotten a bad headache post crash was when I switched to moto/dot. I've ran two DH specific 661 helemts. Almost, every crash I've taken with them has led to bad headaches either immediately or later that day. Even experice longer recovery from the crash while on trail. I can feel it pysically also on my skull from the impact. Almost to the point where I could basically describe the liner design off my head. Yes, all helmets were fitted properly. Reason for sticking with 661, only helmet brand that fitted well with my chimpmunk cheeks. Switched to a Moto/DOT lid and not one headache, no physical pain to the skull. Always able to pop back up with out any hesitation to how my head feels. I understand the theory and point being made here but nothing speaks volume like a real life testing between two products on your own. Just my 2 cents.

I have the same experience as you. I also wear 661 because they fit me best. I definitely felt like I got my bells rung after crashing with my old regular DH helmet. I feel far better after any impacts with my DOT helmet. While a DOT helmet do weigh more (something I got used to) and a lot hotter because of less vents (don't stop riding and ride really really fast ), the reassurance feeling after the crash far out weigh the little discomfort of wearing a DOT lid...for me at least.

Look guys they said that MX helmets are for the high speed. But do you know something about one of the most widely spread MX discipline like enduro ? Those riders use MX helmets at speed that could be lower that speed of MTB riders. You can find the typical example of this discipline here www.youtube.com/watch?v=oMzrM6u1Rks&feature=relatedWhat would you say about that ? In my opinion this article is some kind of advertisment

Maybe because I came from an mx background I know that a motocross helmet is a little over the top (due to penetration tests at highway speeds) but I didnt really think of low speed concussions. Makes me more reassured that my D2 is adequate enough

from someone who rides moto and dh on a weekly basis, i can tell you that all my crashes on both moto and dh feel the same. a digger to the head riding dh is usually worse of an impact than my crashes riding moto. should i ride with a dh helmet on a slow trail ride because the speeds are slower? the logic displayed above does not make any sense to me. more speed does not equal a worse crash.

despite this article, ill keep rocking my SHOEI VFX-W best helmet money can buy and it shows. one helmet for everything.

What the higher speed effects is speed impact. It's the difference between tapping yourself on the head, or thumping yourself on the head. The Danger from crashes comes from the speed of impact, so in that way higher speeds do mean worse crashes

I have always worn a Arai VX-Pro3, for both Moto and DH. I've taken some pretty hard hits doing both sports and have never had a concussion or head injury of any sort. As far as getting fatigued quicker due to the extra weight of a Moto helmet, I'm use to it and it doesn't bother me.

I don't really get why DH guys would go with MX lids unless their riding mainly consists of trails like Whiskey Jack where you can hit speeds of 90km/h. Sure, you can get a bombproof helmet to withstand severe impacts but what about smaller hits? It doesn't take the equivalent of a baseball swing to the head to get concussed (I bet a lot of people would be surprised at the small amount of force needed to concuss a brain, especially if one has a history of concussions).

So if you're wearing that SNELL MX lid waiting for that big impact, you're getting less protection in the lower spectrum, and a bunch of small concussions are just as bad, if not worse than a biggie. Personally, I've had three concussions and although I'm still sane, I noticed some changes (i.e. short term memory isn't as good as it was).

Like chazdog said, this issue needs further research, but until the clouds split and rays of deeper knowledge illuminate the both the leg and fuel powered cycling worlds, I'll stick with common sense, do my homework and buy a helmet that fits my needs.

Not everyone does but body armour with solid plastic plates has been shown to be very little protection. Unless you have something like the 661 Evo suit you're better off protecting the most important parts.

@redrook what are you talking about dude? How is armour with plastic plates 'very little protection' and who has shown this to you? Come to my local trail and we'll both roll down the first rock garden we come across: me in full body armour and you with only your important parts protected. Then you can decide for yourself

Sorry, I was not very clear. The solid plastic armour doesn't reduce impact at a slow rate, which does not prevent broken bones etc, but will prevent bad cuts and road rash. New soft shell pads, that O'Neal / POC and Nuke Proof are now also using (all made by Sas-Tec) are much better in terms of impact absorption and it basically acts like suspension for your bones, putting a good bit of damping between you and the point rocky stuff. When you compare it to hard shell pads and foam its like so much better / safer / lighter and more flexible. Don't get me wrong I would rather have plastic than nothing, but often you can't wear a neckbrace with armour so I would chose the brace, if I could afford one, which I can't.

Testing results on neck braces aren't conclusive, but all the pro's have them (because they don't pay for them!).keep it simple!:

1.helmet , to protect the melon!2.full finger gloves, the first thing that hits the ground (hands)! 3.some form of protector that includes kidney protection , it's easier to lose a kidney/s than snapping your neck!4.knee pads.99999999999999999999.neck brace , lots of cash for a piece of plastic,instead of wasting you money on one get a decent helmet!.

that my friend.. is what i have been saying for years.. but as we have weight weenies.. the road racer is even worse.. he picks weight over safety,.. lmfao. last one died hitting a wall at mucho's miles per hour.. if he had a better lid he would have been better of i think..

Now to get real, how many falls on your head are going to be minor? ALL of the times I've gone down head over clips it's been pinned and straight to the helmet. I just question whether a helmet's priority should be little hits when you usually land on something else in those situations...

This coming from someone who knows the dynamics behind this question, has been through two D3 carbons and is currently riding a SE2.

I think it really comes down to a personal choice based on the type of riding you do... if you ride a lot of fairly well groomed bike park stuff at moderate speeds with big airs and drops, a DH helmet is going to serve you better. If you're racing and bombing through rock gardens at high speeds, the extra shell protection could well be much more important than the extra cushion. If you take a header into a rock garden at 60kph, thats essentially the same thing as an anvil being dropped on your head at speed and the stiffer shell could save your life.

One important correction to this article. A helmets main goal is not to slow your head down.. It is designed to slow the rate at which your head slows down during an impact. If you were to simply slow the head down quickly, you would increase the force on the head. To reduce the force on the head you are trying to extend the period of time that the head deccelerates, thus reducing the force.
This doesn't change the argument, however it should be correct to avoid confusion.

One other thing.. The speed of the vehicle is only a small part of the problem. The real impact on your head is based on a change in velocity when your head comes into contact with something. If you are comparing a motorcycle going 100 km/h on the highway to a dh bike going 30 or 40 km/h. The dh bike is much more likely to have harder head impacts, with trees for example. If you hit a rigid structure at 100 km/h, you dont have much of a chance with any helmet. The idea is that during most accidents, the change in velocity is much less that 100km/h. If you t-bone a care for example, there would be a smaller change in velocity as the rider is thrown over the bars, followed by another when the rider impacts the ground, then the rider would have a time to deccelerate while skiding to a stop. This is obviously not always the case it is reasonable. If the rider was thrown over the car and into a wall, the impact would likely be fatal.

One the other hand if you are thrown from a dh bike and land head first into a tree or a rock, theres a decent chance that your head will experience a change in velocity of close to the riding speed before the crash.

I'm not trying to argue for one helmet or the other. I just feel that this article, and some of the responses, are linking speed of the vehicle be the driving argument for one helmet type versus the other. The actual impact that must be withstood is due to the change in velocity that the head experiences over what period of time.

A big issue I have with helmet manufacturers and retailers is labeling. It's either impossible to track down a list of standards a helmet meets, it's buried in layers of fine print or it's completely mislabeled from website to website. Take for example the Giro Remedy, it's only the Remedy CF that has the ASTM certification and not the base model. But it's incredibly easy to miss unless you just happened to have been switching back and forth between both models on Giro's website and noticed the slight switch in the "features" list. Lots of retailers have it listed wrong on their websites as well.

I agree that it should be clearly labeled in any spec list. I see plenty of "14 vents" and "Graphics by Herbie Hancock" but rarely a full list of accreddited certifications.

Are you sure that the lower end remedy is no longer ASTM? That was the whole reason that helmet and standard exists. I'm willing to bet it's a website glitch. I have a lower end remedy, which I bought specifically because it met those standards...

Ive blown the full face part out of mtb full face's, not a good time. also seen friends pretty well explode good mtb full face lids. When I used to wear them it almost felt like the back of my head was unprotected and wide open. No thanks I'll stick to my tld SEair for dh. Anytime Im riding slower its on my AM bike in a half face anyways

I think this article left out a really important aspect of head protection, rotational forces which causes a lot of damage on your brain. As far as I know only Poc has taken that seriously with their MIPS-system. If they weren't so damn ugly I would wear one (fashion over brain!) but I really believe it's the safest DH lid.

Another thing is that a lot of carbon lids are a lot stiffer than composite lids which might make them less safe in some cases but of course safer in other.

A third thing is the question about weight. While my TLD Air mx helmet is pretty damn heavy, My One Gamma mx helmet is lighter than my old Giro DH helmet so you can't say that a DH helmet is lighter than a MX helmet. In most cases it's probably true but you should make sure it is if you think that's important to you.

All I'm saying is that it might not just be DH vs. Mx but also model vs. model and material vs. material.

I have a shoei MX helmet and I will 100% trust that more in protecting my head than any Dh helmet. You also have to take into account the padding inside the helmet and Dh helmets for the most part lack in that area

This might shock people but in a serious crash you want the helmet to "break" as it is an impact attenuator. The breaking requires energy and results in a less serious trauma for your head.

As for the foam if it is too stiff your head will experience a larger force than with DH engineered foam. As a result you willl experience more brain trauma from a MX helmet with stiff foam. The world cup riders could possibly be on the limit of DH helmets but it seems doubtfull as they are the testers of most products. It's quite likely the helmets are modeld around what they experience and need to withstand.

Not entirely convinced by the part about the spikes, I think you could easily encounter very sharp objects on a DH track.

I have split a d2 carbon in Half and almost had the rock come through the shell. I have smashed the shit outta fox v3 and split it in Dam near two. I currently run the top of the line shoei vfx lid and it's hands down the best lid out there. Top guys do t use moto lids abuse they don't want to or half to moist of them have never had a bad head injury either. They are confident I. There abilities and equipment the same reason not everyone wears a neck brace in either moto or dh. Your personal protection is your own choice. I love my D2 carbon helmets I have had them scince they have come out 7 total. I feel much safer with my moto lid on especially at high speed. Do some research on the higher end list made my real helmet companies like shoei.aria and you'll see that there a multitude of saftey features built in that mtb lids don't have. Once again personal choice the one thing I stress is not to cheap out on your lid I have scene to much carnage in moto and dh from inadequate head protection. And I've been riding and racing at top level for 25 years.

So, there's good reason not to choose a moto helmet, but I think there are a lot of good reasons not to choose a pure MTB helmet too. I'd love to see a followup article on the ASTM 1952 standard, and some general comments about MTB helmets. I for one would never trust my priceless dome to an ultra-light bicycle helmet....that's why I opt for the ASTM DH standard. Nowadays, you virtually never see a pro in a cheap (MTB) helmet. They're all in moto or ASTM helmets. Most or all of the Kali helmets do not meet ASTM standards, nor Moto, and that makes me hesitant to pick one up for DH.

IMO this article is total bullsh!t and oversimplified to the point it makes no sense. Every single piece of anecdotal (real world) evidence from people who ride both mx and dh, and people who have used both types of helmets point to the mx helmet preventing concussions moreso than a dh helmet. Many high quality mx helmets have multi-density EPS foam liners to address the issue of different impact forces in different crashes. Shoei uses a shell that is flexible but is made of materials that will resist penetration. TLD's own D3 helmet is MUCH closer to an SE2 mx helmet than their own D2 dh helmet. This article assumes that in riding mx you will experience much harder impacts, but this may not be true... you are the same distance off the ground either way. The potential for either soft or hard impacts to the helmet exist in either sport, it depends on the particular crash or the way you fall rather than if you're on a bike with a motor or not.

This article was great! I really liked his analogy of the helmet foam to bike suspension, I think that makes it much easier to understand for a lot of pinkbike users. It's like how pro DH bikes are set up super stiff and the suspension doesn't really start "working" until you're up to some pretty high speeds. For most people, that moto helmet will feel super rigid and maybe rock your brain more on those little tree-branch singletrack impacts, where a DH helmet might flex and be more comfortable. Save the moto helmets for high speed DH courses or something!

but, is DOT = Good?or is DOT too much?I do believe Moto helmets fit much nicer for much less money. You can get DOT moto helmets for $70-170.How about Fly Racing Kinetics? They have a dual density foam for highspeed and slowspeed impacts?

I'm assuming you guys have watched a SuperCross race before, or especially James Stewart. Those guys lawn dart 20 feet all of the time in motos (LOWSPEED IMPACTS) and knock themselves the f*ck out.

Look guys they said that MX helmets are for the high speed. But do you know something about one of the most widely spread MX discipline like enduro ? Those riders use MX helmets at speed that could be lower that speed of MTB riders. You can find the typical example of this discipline here www.youtube.com/watch?v=oMzrM6u1Rks&feature=relatedWhat would you say about that ? In my opinion this article is some kind of advertisment

sad truth is my fullface is old and beat to pieces, but I can't afford a new one when I only use it 2 or 3 times a year. The rest of the time i have a skate helmet (with a softer liner than Styrofoam xc helmets) that saves my head and feels way better after an accident. I do have an xc helmet I use for trail riding but when it comes to knocks I like the skate helmet best.

I rdie a DH helmet or a skate helmet depending on the riding and there is certainly no need for a mx helmet. they have saved me from some hard hits concusion free. Reading that stuff about concusions is worrying tho after having quite a few (non riding related). oh well still gonna ride!

Interesting, i've had some big offs in both of my old giro remedys, and in my current 661 flight 2 helmet. Am no helmet expert in any way, but i can easily flex and distort my giros by hand but not so easilymy 661 moto lid. I have however found that though it is a stiffer shell it has got about twice as much foam padding inside, leading to a) a better fit, important for protection b) good small impact absorbtion.

Despite this article, I still personally feel safer in my mx lid, and thats largely what matters to me. If i dont feel safe i cant ride fast, having cracked and destroyed two remedys in just over a year i'm sticking with motocross lids. Its also worth considering that high level dh is achieving motocross level speeds in places, on ground featuring rock gardens and other features with high impact and penetration potential (the reason for the troy lee d3 beefing up over the old d2). Ultimate protection is still important, like the neck brace for example, you'll risk a bone for the sake of your spine, i'll risk a small concussion for the sake of my skull.

Interesting article thats added meat to a malnourished issue, but i'm not going to decide solely based on one article based largely on information from 7 years ago. This issue needs further debating and research, would have been good to get troy lee, bell and 661 involved as they all are the big moto and dh helmet makers, no offence to kali.

Your remedys cracked because they were doing their job, breaking so you don't have to. Just because something feels like it has more padding or whatever doesn't mean it is more protective, you don't know what forces are going on in there when you crash. Feeling safe is not a credential for a helmet. Theres no such thing as a "small" concussion (i.e a brain injury!), and any brain injury is dangerous. Use your mtb lids and psych yourself up. You can convince yourself it needs more debate or whatever, but thats exactly what climate change sceptics say too, because it gives them an excuse not to do anything. Get an mtb lid, or keep risking your brain.

yeah fine, all makes sense i loved my remedys, thats why i had two, but one article by a few people has yet to convince me, call me a cynic, but i also value the dot and snell standards developed by testers over years who also know a few things about safety. Not gonna jump on the mx lids are bad bandwagon based on this article alone.

When the first guy said, "hey maybe the earth isn't flat" everyone probably said he was stupid too. SNELL etc were not testing for mtb impacts AT ALL so their material is almost entirely irrelevant in this debate. Do yourself a favour and get a proper lid, it's not just this article, none of this is new. Dirt did a similar article two years ago (sorry cant remember the issue).

I have had one Giro Remedy helmet. It cracked on impact(along with my wrist and parts of my bike) and the foam compressed a good deal. I still woke up in the hospital and have no memory of crashing or good parts of that day, but I'm glad the helmet wasn't over engineered. Simply thing is, it worked and for about $100 to not be a vegetable for the rest of my life is awesome. I never actually looked at the rating for it when I bought it or really cared. It was a cheap full face helmet. I don't know about any of you, but I really look into what I'm buying now when it comes to all safety gear and cost really doesn't matter anymore. We spend a ton of time looking at what's the best stuff for our bikes, but when it comes to safety I think most people look at what is the cheapest, most stylish, or what our own personal opinion is on what safe is.

I'm with chazdog on this one. I own both a Giro Remedy, and a ONE Kombat. My remedy does not fit well, and offers little padding. it was only offered in sized that either wouldn't fit my head, or fit way too loose. my Kombat was offered in more sizes, and offers more padding leading to a MUCH better fit, and it sucks up small hits much better. i will stick to moto Lid till i find a DH helmet that doesnt feel like an over built xc helmet

Just because you think it offers little padding doesn't mean it wont protect you. Your opinion means nothing in the face of actual evidence. You can flex pro hockey helmets like nothing else but it's all for impact dispersion and absorption. If it doesn't fit then get a helmet that fits your head.

Padding means nothing. It stops your head bumping the helmet, but on any impact bigger than what you could comfortably stand without a lid on, it wont make a difference. When the say 'small bumps' the don't mean hitting your head on a branch they still mean a decent smack. Also you can't base your decisions on motto/DH lids on giros fit (i agree fit is important) but when buying a lid you should check the fit, and buy what feels best. You are all also commenting on one of the cheapest DH lids out there vs some pretty expensive motto lids. Think about it, DH lids are designed for DH, MX lids designed for MX, it's not rocket science. You wouldn't turn up to a DH race with a MX bike would you? Things are designed for what they say they are, and are designed like that for a reason.

i'm not in a market where i can walk into a shop and try on a hand full of helmets. in the helmet's that i've used, i feel that a good shot would have me puking. i'm not going to put my personal experiences aside for some pinkbike article which offers little in the way of numbers. this tech tuseday is little more than an opinion piece and an add for Kali helmets... i'll keep my moto lid till i see numbers

Look at it simply, motocross bikes travel faster, they need better helmets to cope with the higher impacts of possible crashes.DH helmets are engineered to be lighter (therefore cheaper and more aesthetically pleasing) because there aren't as many certification tests they need to pass because DH bikes are slower.

Do the bloody math. motocross lids protect you better!

Why would MX riders still be using MX lids if DH lids protected better?

You guys just believe anything a couple of people say when writing an article with basically no credible back up sources of info.

i love the idea that because of this article my motocross lid might as well eb a baseball cap. It still offers massive protection, i am not dicing with death wearing a helmet that withstand more then a dh helmet. I worry about pinkbike sometimes, did any of yu actually rear the other articles this linked to and they to form an (key word here) objective opinion?

the helmets should be classed for riding styles. Moto racers need harder helmets than rec riders and mtbikers because they generally encounter harder impacts. after a big crash a helmet should be replaced anyway, so a helmet that deforms could dissipate more energy and offer more protection.

i ran a moto helmet for a bit and it felts solid. Then i got a DH helmet and when i crashed it gave me a head arch.
But I believed when the said stiffer shell is worse because i have had probably my worse crashes in a half shell and my head felt fine.
You definitely need a helmet better for small crashes because most of my worse crashes on a DH bike are on silly little low speed crashes.

People are acting like Pinkbike is some sort of corrupt government trying to pull the wool over our eyes.
This is Pinkbike - the biggest 'people's' website on the Internet! They wouldn't have said anything if it didn't matter.
Listen to what these extremely experienced people are saying.

To this day I can't recall seeing someone wearing a Moto helmet for mountain biking, and well they are BUTT ugly. As far as I'm concerned my D3 has proven it's self and not just for me but others ..and it' SEXY as hell.

Tried all dh helmets from giro, bell and troy lee. The problem with dh helmets is too many vents. Any hole in the helmet is potential death where i ride. I have a troy lee d2 and se right now. If i riding plattekill its the se, mt creek i wear the d2 because the speed is much slower. You can get away with a dh helmet but the troy lee se is the best fitting and best vision. Jeff Ward knows something about going huge and that why all moto, snowmoto and big huckers everywhere use the se. The better you can see out the helmet less chance of crashing. The se very light also compared to other dots.

For you out there that don't believe racing dh cannot generate the forces to justify a dh lid. You probably not at a riding level to comment. In reality top dh racer spend more time at flat out speed than motocross racer. And in moto there are no trees it's all open
Space in sx and moto tracks

For myself I will a moto lid for the rest of my life.I have had several bad concussions and knock-out in mtb full face lids from various brands.I now have been using a moto lid for 2 years and have not had a head injury despite many crashes.Most moto lids also go down further to offer more neck protection.

And I passed up a Kali Avatar the fit me extremely well, for a helmet that cost $100+ less, the Urge Down-O-Matic. Urge was much lighter, much more low profile, and felt a bit stiffer, but wasn't DOT or SNELL cert'd. I wonder if that was a good choice, after reading this. To say the least, I know the visor offers some absorption--I had a ~20 mph faceplant, that tore one side of it off, and I got away with just a face full of dirt and sand.

I recognize that this post is like four years old, but I wanted to note that I pulled up the ASTM F1952 standard at work and it allows a maximum impact of 300 g's - which is 25 more than the "too stiff" SNELL standard of 275!!

Neither the amount of money a helmet costs, nor the (negligible) weight of the helmet should EVER be considered for anyone considering buying a helmet (of ANY type).

What this article failed to shed light upon is the fact that, yes, moto helmets are not meant for downhill, but they arent meant for MOTOCROSS RACING ON DIRT TRACKS EITHER!!!! They are meant for extremely high speed crashes into pavement. With no rocks or trees. I have personally witnessed multiple pro-level mtn bike racers who crashed while using mountain bike downhill-specific helmets. They completely destroyed the helmets, and were put into severe comas. AND can now no longer ride any type of bicycle, and struggle to perform basic functions in day to day life. TBIs are dangerous.

So I guess the question is- would you rather be "saved" from the small and medium impacts, since they "matter'???? Or would you rather have some small concussions, albeit with some brain damage------- but still be able to function in your daily life????. F*** this article

My Son rides Mt Prevost. Tough, fast, technical, and gnarly...No less than Steve Smith honed his skills on Prevost.

With my Son my primary concern is a high speed impact with a tree or rock. If he has a serious impact is is going to be a brutally hard hit. For this brutal impact I side with the DOT dirt bike helmet...What it was designed for right?

Of further concern to me is when I fit him (or me) in a Troy Lee, Fox, or Giro I can push these helmets forward into his/my mouth...This bothers me.....While head protection is primary, teeth are also on the list..Have a helmet slid forward into your mouth and say goodbye to your Chiclets!

As an MX guy I remain unimpressed with some of what I see in DH MTB helmets.Cheek padding needs to be upgraded from fluff to something more substantial....This is what holds your face back right?The helmet nose needs to be long enough to give your teeth a fighting chance.

The faster you are and the harder you race the more helmet you need. The flexy thing makes sense...Upgrade the rest of the DH helmets to suite race pace and I will be a buyer. Until then I consider what is currently on the market good for slower weekend warriors.Just my opinion.

Thanks for the comment. I wrote the article, and I can definitely see your perspective on things. I raced motocross for more than 20 years -- seven as a local pro -- and I'm now a Cat.1 DH racer. When I first started riding DH, I just used my moto helmet. But since then, I've read and witnessed a few things that suggest to me that most moto helmets are probably too stiff for MTB use -- if not motocross and highway use.

I wish that Motorcyclist hadn't removed the article from their site that I referenced above, as it was very thorough in describing the problems they found with SNELL helmets in their testing. That said, the NYT story linked to in the article covers some of the same ground in suggesting that stiffer helmets aren't always better -- even in some very high energy crashes. And in my experience with MTB, most of our crashes fall well below the threshold that SNELL and even DOT test for. And that would be fine, except that the stiffness employed for those worst-case-scenario impacts could make riders more vulnerable to serious or even life-threatening injuries in the types of crashes that are most common in motocross and DH.

I ride Northstar in Lake Tahoe and a lot of other brutal DH courses here in the area, so my own head protection is very much on my mind. For what it's worth, the most substantial DH helmet I've tried on is the Fox V3R, which has a very moto feel to it, with a larger shell and more padding than most DH helmets (including Fox's lower-line models). It's also certified to the ASTM standard mentioned in the article. If I were looking for something for my son to wear, I'd definitely give that one a look (and for the record, I have no relationship with Fox). Thanks again for sharing.

The stiffness of the SNELL helmet is indeed overkill for 99% of what we do and your point is both well received and appreciated.A more flexible design is definitely on my radar now as we are in the market for a new helmet.I have not seen the MTB Fox V3 in person, but until recently we have been looked long and hard at the MX V3R and it seemed a decent choice, but(after reading your article) turned it down because of the SNELL cert.Looking online the two helmets appear to be identical, are vented the same, they are both constructed of CF, and they weigh exactly the same (took some homework, but I found the MX/MTB helmets weigh identical).I would be very interested to hear if you know these to be different helmets or is the paint job just different?

The MX version is SNELL rated and the MTB version does not have the SNELL cert, however I wonder if the MTB helmet may be the same helmet without Fox having sought SNELL certification for this particular version?I assume FOX pays considerably for SNELL certification and I wonder if they just pass it over to save money on the MTB V3?

Thanks in advance for your help and thanks again for the great article!Peace

perhaps the end question could include an option for those of us who already have used our common sense and got a helmet designed for the sport we are doing, instead of assuming every person reading this article buys MX helmets for DH...?

Good article but from what I understand the real issue hasn't been solved or talked about in this article. The sloshing effect of the brain after contact with your skull is what causes most damage and there is no helmet that will prevent this. Will there ever be, that is the question we need to answer. More articles like this would be great though, informed riders is always a good thing.

Yeah yeah slow hits and fast hits, wtf this is obout, does the helmets have hight or low speed compresions?NO> THEY ARE JUST HELMETS, dh helmets are lighter and have better vintilation, mx helmets are bigger , stronger , stiffer = more protection, but in the other hand they weight more and vintilation system is designed for highter speeds mostly.

The Kali Durgana Medusa is a awesome helmet, I switched from a Hard Rock Hustler Moto helmet can't be happier, much lighter, cooler and enough cushion that I feel confident I'll survive a crash with little injury.

a primary safety concern in choosing a helmet is the weight. A motorcycle helmet is much heavier and will put much more strain on your neck in a crash (provided that you don't wear a neck brace). Imagine your head snapping around like a rag doll with that heavy weight on your head.

This is only one small part of the story as I'm sure the experts will appreciate. The choice between helmets should also be influenced by changes in inertia due to weight/ interface with neck braces/ etc. Unfortunately no-one really has answers to what is best and testing standards and methods are oversimplified and largely inappropriate. Some recent studies suggest that in certain situations you are actually better off without a helmet due to the weight of even an XC helmet but I'm not sure I totally agree with this! I thoroughly applaud those who are trying to clear all of these issue up though and great article PB

For all of you who are looking for some more information about helmet and certification, i found this website www.bhsi.org. A very good and updated!! I'm in the market for a new helmet cause I've had a concussion 2 Weeks ago (I had a O'neal Fury). I never been so confused about DH helmet since i both my last one. I get headache just thinking about it. I'm a little surprised that no one ever mention using a mouth piece will help too...

i would like someone to anser this plz-- i have been using the same giro remedy helmet for about 3 years now and I have had lots of hard impacts on it. Never have I once been severly injured wearing it except for a few headaches. but should I get A New one? I have a big full face moto helmet but its rly heavy so i prefur not to use i for biking...

dress for the ride not the crash
i find a DH lid more comfertable than MX cos the extra wieght of the MX lid can throw my head around when hitting impacts like big drops
if im more comfertable im less likely to crash but, hey thats just me

If you think about it, the heavier the helmet, the more likely you are to have neck-related injuries due to the extra momentum a heavier helmet has.
If you are wearing motorcross helmet and you crash in any way, it is more likely that you will be injured from whiplash than if you were wearing a DH specific helmet. That said, at higher speeds, it's probably safer to wear a motorcross helmet...

Great article, but why does Australia have the most stringent standards for helmet manufacturers to meet?? are our brains more important than anyone elses or do we have bigger crashes?? My understanding is that a helmet that meets SNELL standards will be comparable to the latest australian standards, but a lid bought from the UK will not, and hence, cant be used for racing. does anyone know why this is the case? it is precluding alot of good quality lids from being imported to australia, so we have a minority of brands that can price gouge and charge whatever price they want for a decent lid.

The Aus Standards (Hereby known as AS) are a mix between DOT and Snell, both DOT and Snell approved helmets pass AS testing but the helmets are not allowed the required AS certification unless the manufacturer provides a certain number of lids to AS for destruction. So Even though the model purchased overseas is the EXACT model purchased in Aus, if it does not have the AS sticker in it, it's considered illegal to wear on the street.

The downside of this is that some of the smaller manufactures (and Aus being a much smaller market than elsewhere) cannot justify providing these helmets to Aus Standards out of their own pocket on a yearly basis and for every model, so they do not get sold in Australia as they have not passed AS Certification.

So... to summarize... Dont get a SNELL rated helmet for DH, but a DOT or ECE one is just fine? Although the lighter biking specific one iwll be best? Did anyone else pull that sentence out of 6000 words?

I think a lot of people fail to realize that helmets albeit expensive are supposed to protect you first and foremost. Buying a mx helmet for even the gnarliest of dh and freeride riding is a very very unsafe move. I understand that people can't afford a mx helmet and a separate dh helmet, but why sacrifice that fancy carbon fiber bar or titanium railed uber light saddle for a good helmet that will hopefully outlast your bike.

The best way to look at this is an analogy, would you rather drive a 3/4 inch thick steel plated car around or a standard car. Which would be safer? You might say o well if I hit something with a armored car i will just destroy whatever I hit (the hummer/big sub theory) but realistically in a bicycle crash with you head meeting tree, rock, earth the tree rock or earth will win. Dh specific helmets are like regular cars designed to absorb impact not just transfer it to your body. Another great example which maybe someone can speak to that has been in the situation, when an armored vehicle (or effectively an mx helmet) is hit with a huge amount of force say running over an a mine or explosive charge, the people inside are safe (which is better than dead) but are shaken up pretty badly (i don't mean bruises either, very serious permanent damage!!)

This has definitely changed my view on things but I tend to take a full face helmet and a cross country helmet when I go to trail centres . I bought myself a 661 helmet last year and apart from being slightly hot It's always in the car just incase . I think as long as your careful then a good XC helmet will do for most trail centres but theres no doubt a full face is a good idea all the same . Great review though definitely a controversial debate

be better off with the THE, the snell approved moto helmet wont protect you from......anywhere near aswell as a dh specific helemt. read the article yourself, i cant be arsed to type it all out for you.

Your THE helmet had taken a few crashes, and you have had 5 concussions? Dude, you're meant to replace your helmet after any significant impact, which it would have been to have given you a concussion. Any full face helmet would be better than using a crashed one, even if there is no visible damage...

Your helmet has SNELL protection to protect motorbike riders from motorbike crashes. Your riding a mtb and you will have mtb crashes. It seems very solid because it is too solid for your needs and will greatly increase your likelihood of repeat concussions (which if you knew anything also means increased risk of permanent brain injury). If you have actually had 5 (I have had 2) then you should be very interested in what works best, not what your layman's opinion reckons is best.

I've bought a fox V3R carbon helmet and people will ask me why i have a moto helmet, but the V3R just has the same shell and the same amount of padding, but for the V3R (mtb specific version of the V3 which is moto) fox have adjusted it to this new 'mtb specific' technology, but I have still noticed that there is a lot more protection in my fox helmet (which is basically a moto helmet) than in any other mtb helmet I have owned because of the greater amount of padding.

I have to admit I am becoming highly highly frustrated with how unbelievably fu**ing stupid people are being about this. Aron Gwin, and of all people some BMXers are in no way creating impacts suitable for an MX helmet!!! Unless downhill courses have become a long stretch of tarmac with brick walls in the middle designed to generate 75mph speeds (what do I know I haven't raced since October) then their just as misinformed as you are! I have how "but, but the pros do it" is an argument against science!!! Its fuc*ing SCIENCE!!!!!! SCIENCE!!!!!!!! Maybe you all need a couple whacks over the head. Like holy crap people cannot ever just abandon a belief can they? No matter how fuc*ing obvious it is! This is why people smoke cigarettes isn't it? Brilliant really how that all works, dumb people cause harm to them selves thus kill themselves off; alto society has become so fail safe that it doesn't work like that anymore so now we just all have to live with you morons wandering around polluting society with your presence! Oh and your MX helmet makes you look like a bobble head.

Ok I want to comment on this because you say it about science. I believe there is something here that a lot of people seem to be missing. The speed that you are going on your bike doesn't determine the impact that your head is hitting the ground. You could be going 60 mph on your DH bike, nail the ground with your body, (which absorbs most of the initial impact) and then smack your head, which results in a low impact hit to your head. It's all about the acceleration that your HEAD hits the ground at, and HOW it hits the ground. Remember that F=m*a. The faster your head is accelerating towards the ground, the greater the force that it will encounter. Say you're going 25 mph. Yet the way you fall creates a massive whiplash. This is causing your head to accelerate and high rates towards the ground, which in turn creates a large force to your head. This isn't science. It's physics. Lets clear that up. I have ridden DH helmets and Snell helmets alike. I've hit hard to the point on a DH helmet where it cracked and the front face protector smashed in towards my face and looked like a bulldog-esque helmet. I was very concust. I've had the same type of crash with a Snell helmet (high acceleration impact) and was very glad I had it on...little shaken up but no damage. Low speed impacts on DH helmets, sure it's fine. Low speed on Snell leaves you a little rattled but able to ride. That being said I have both types of helmets. It depends on what I'm riding or how I'll be riding to determine what I will wear. I haven't found anything wrong with my Snell helmet yet that would make me want to sell it. I'm interested to check the buy/sell after this article and see how many Snell helmets are for sale.

Best quote I've ever read on here. Krash, you are obviously very confused. A "little rattled", is that the medical term? Lets just clear this up, you're talking out your ass. "When it comes to brain trauma, small and medium-sized hits matter" - read the f*cking article dumbass.

You are right about the speed correlation here krash. The speed you are going on the bike isn't the only factor in determining how fast the head hits the ground. Its the way you fall. I mean a simply example is you are walking down the street, or walking down a couple steps and you trip and fall. Your body isn't traveling more than a couple mph, but you can be sure than your head is traveling much faster that that by the time it whips down an smashes the ground.
That being said the DH helmets are probably the better choice for many recreational riders. But I can see why guys on the pro level or other very experienced riders who go much faster than us weekend warriors would choose the MX helmet, as they are likely exposing themselves to a much more severe potential impact.

To start, the physics of it is, if the helmet smashes your head doesn't, but that takes no genius. The whole point of this article was the biology "When it comes to brain trauma, small and medium-sized hits matter". The new discovery isn't that motto lids are stiffer, we knew that, but that concussions are much more dangerous than was thought. Like someone commented above ''If you wore a flak jacket everytime you went out in fear of getting stabbed but often ate greasy foods the end result would probably be the same, difference being the odds (i.e. you're much less likely to get stabbed).''

this is definately an interesting article and really just confirmed my rationalization on this topic ie if your riding moto wear a moto lid, if your riding a DH bike wear a DH helmet. if there wasnt a difference then all the big companies that make both wouldnt waste time and money making two different types. also some of you make some good points and im no physicist but if F=(m*a) wouldnt the added mass of a MX lid only increase the force indured by your brain?

I'll apologise up front for how long this is, hopefully it'll pass the spam filter in 2 parts. Since people have started trying to use physics to explain this can we at least attempt to apply it correctly, notwithstanding the considerable complexity of this biomechanical context which I’m about to grossly over simplify.

Yes, F=m*a. Acceleration (m/s^2) is the rate of change in an object’s velocity (m/s). In a physical system, velocity is measured as a vector , ie. it has a direction within the 3D field which is the resultant of the sum of all the component inputs.

For example, assuming you are riding forwards on flat ground when you crash. You go over the bars while doing 16m/s (about 50km/h). Assuming that you end up 1.5m off the ground before you start coming down again, V^2 = Vo^2+2a(X-Xo), then you are falling in the Y axis at about 5.4m/s when you hit the ground. Velocity is a vector though, so you need to add the 16m/s you were doing in the X axis. The resultant vector (since this example is only happening in a 2D plane, apply simple trigonometry) V=16.9m/s.

In reality when you hit the ground you’re not actually going to stop dead (pardon the pun), you’re head is probably going to bounce. That’s too hard to explain without diagrams though so let’s keep it simple and assume you’ve hit a tree. This brings us back to F=m*a.

Part 2: I kind of glossed over this earlier, but when you’re falling acceleration is the result of gravity. When people talk about the force applied to your body in a crash, that is actually negative acceleration also known as deceleration.

So your 58cm head which weighs say 5kg + about an extra1 kg for an mtb full face helmets weighs in at 6kg. Your helmet is decelerating against the tree, going from 16.9m/s to zero m/s essentially instantaneously. In order for the maths to actually work though we’ll need to assume that your helmet takes 0.1s to slow to a stop. So a = 16.9m/s / 0.1s = 169m/s^2. For comparative purposes gravity is about 9.8m/s^2.

As you can see, relating back to G’s gives a somewhat opaque representation of the actual magnitude of the impact as it ends up expressed relative to your weight which hides the real world impact on severity as a result of increasing helmet weights.

Similarly, the 17.2G can’t be related back to the 275G limit set in Snell M2010 as that is a measure of how much of the force generated by a 500kg anvil with a surface area about 11cm square hitting the helmet at 7.75m/s transfers through to your head. Incidentally, that equates to 38,750 N or about 645 G. Even top fighter pilots and astronauts have blacked out by the time they reach 10G, yes I know it's a completely different mechanism but it gives an idea of the general limits of the human body compared to these tests.

Part 3: This is all a very long winded way of saying that when it comes to how ‘hard’ you wack your head when you crash, the only things that actually matter are how fast you were going when you hit the ground, how much you, anything attached to you or anything that hits you (such as your bike) weighs and how quickly you stopped moving. It could be suggested that the test impact SNELL is seeking to mitigate is orders of magnitude (implausibly?) high when compared to the sorts of impact forces an mtb rider is likely to actually experience in a crash. And as the article suggests, perhaps the side effects of compliance with such a high standard is not necessarily in the best interest of mtb riders.

An engineering standard or specification such as M2010 responds to a documented set of required performance criteria. Therefore it WILL NOT give an optimal functional outcome for a completely different set of criteria. SNELL and DOT aren’t even targeted at Moto Cross applications, they’re designed to cater for Highway environments. If you crash your Hayabusa at 300 km/h SNELL is probably spot on, you’ll be dead anyway, just not necessarily from head injuries. Motocross helmets need to comply with the same standards so that you’re allowed to wear your helmet from your garage to your nearest MX track, not because it’s the best protection for you once you’re off road.

MX riders experience higher speeds it is true, but MX tracks are designed/engineered to save lives and to minimize impacts...DH MTB...Not so much!

MX tracks make sure they do not have trees and giant boulders in the middle of the track for the rider to hit....Dh courses are littered with potential death traps. Hitting a big tree or rock with ones head at only 15 MPH or less could be life ending. At 30 mph it would be life ending....There is no MX comparable here...Something to consider.

Last weekend my Son rode with a soon to be pro MX star. His father (my buddy) rode with me in the shuttle truck and we compared notes...After comparing notes our thinking that DH is much more dangerous than MX....Surprised? I was!

Comparing notes on injuries per race there were many more on the DH races than at the MX track. Every local DH race this year had major injuries (ambulance and broken bones or worse). According to my buddy about 30% of the MX races have a crash that involves an ambulance or broken bones. Considering how long the MX guys ride for (20 minute moto, plus qualifying, plus practice) the differences are staggering!

I wonder if in part this is a result of MTB riders wearing lessor protective equipment?I thought you might find this interesting....I certainly did.

Interesting. In my years at the track(s), I've found the opposite to be true. I've only seen the races interrupted for injury at the DH events once in the last two seasons, but in moto it was a good day if we made it through a single race day without an ambulance run. I suppose the difference in perspective could have something to do with the fact that we live in different places, though speaking from my experience, my moto crashes have typically involved a lot more energy than the MTB ones -- or so my doctor tells me.

In any case, I do think moto seems to be accelerating a bit in terms of injuries lately -- today's four-strokes are so fast and today's riders are so skilled that it seems like a lot of riders spend endless spans on the injured list. This is Racer X's injury report midway through the 2012 MX season: www.racerxonline.com/2012/06/15/injury-report-budds-creek

Again, I certainly understand your reservations in the helmet debate. As a dad, it's up to you to follow your conscience in choosing your son's gear. My article wasn't meant to condemn moto helmets or their designers; I only wanted to provide some often-overlooked bits on the helmet debate as it pertains to DH. Good luck, and have fun out on the hill with your son.

While softer shells do make some sense concerning impacts, its not the small impacts that are going to severely injure you, its that one big one that comes once a year or so. Iv seen a DH helmet rip in two upon impact with a tree leaving the rider with many broken facial bones. Too soft of an outer shell perhaps? Idk if it has been implemented yet or not but it would be very cool to see helmet manufactures mold the shell outer to different thicknesses depending on where the helmet needed stiffness similar to carbon bike frames.

Something else to note; Once the inner foam has been crushed or compacted it is far less equipped to dampen impacts in that same area. A softer helmet could sustain multiple small impacts that compress the foam and then leave little protection for the big impact.

Im pritty sure that when you once crash the manufacturers sate you have to replace it beacuse it can only take one impact and offer full protection. Also I've only ever used 661 helmets at £80-£110 beacuse its all i can afford. After taking two big impacts where my head met a nice six inch diamater root and then a rock in a row on the side of my head in the same crash i was fine with no concussion but the helemet was shagged. So i will be sticking to DH specific helmets

Also the article said that there is new evidence concerning DEATH linked to soncussions whichyou sustain from small impacts. if thats not a serious injury i don't know what is.

Quite true but the link to concussion and death may be a new one but it doesnt mean that stringent experiments and investigations have not been undertaken.
Also mountain bike riders are more likely to have these low impact crashes which cause concussion which then can scar the brain causing damage. And when in the article they talk about high, medium and low impacts its in realtion to what a motor bike rider would sustain. Im not saying landing on your face from a huge drop is not serious or hiting a pointed object but these are still not to the same force as a motorbike rider would sustain from hitting a truck or if racing say the TT in isle of man and hitting a wall at 120 mph.

chazdog: obviously, but you can't neglect the smaller impacts. If you wore a flak jacket everytime you went out in fear of getting stabbed but often ate greasy foods the end result would probably be the same, difference being the odds (i.e. you're much less likely to get stabbed). Same on a bicycle, you're much less likely to fracture your skull than to have less severe impacts, which can accumulate to very real consequences.

Forgive me for not remembering his name, but I saw a documentary on a skier who was famous for having spectacular crashes. This buy was no bloke, he raced on an international level. Once, he crashed while skiing with his family and it was one too many for his brain to take. Now he wakes up every morning to his wife showing him pictures of his family because he doesn't remember them. His memory ''resets'' every time he goes to sleep.

This is an extreme case but it goes without saying that impacts to the brain, even the smaller ones, DO have consequences.

On the BMX seen, several Pro BMXers have been using MX helmets while racing on the SX tracks. The speeds those guys/gals are going now, and the distances for the jumps have really taken off these past few years. I'm not sure a DH helmet is enough for those tracks.

SNELL = Bad but, is DOT = Good? or is DOT too much? I do believe Moto helmets fit much nicer for much less money. You can get DOT moto helmets for $70-170. How about Fly Racing Kinetics? They have a dual density foam for highspeed and slowspeed impacts? I'm assuming you guys have watched a SuperCross race before, or especially James Stewart. Those guys lawn dart 20 feet all of the time in motos (LOWSPEED IMPACTS) and knock themselves the f*ck out.

It's not so much a matter of bad and good, as relevant and irrelevant. DOT is fairly irrelevant for the most part unless you're wearing a helmet to protect yourself from a falling anvil in a controlled environment.

You can't really compare MX/SX accidents because there is a lot of weight behind the bike. They have some pretty catastrophic accidents at low speed. IMO it's more important to look at individual helmet design and construction and use some common sense. Some things to consider: many companies use the same helmet manufacturer. In MX, O'neal and ONE Ind have typically been made by KBC. And they're not the only brands. Look at companies whose origins ARE helmet manufacture and design. These are the guys who do the R and D. Also, most of the better helmets will use a multi-block foam design to assist with getting the right amount of shock absorption depending on the area of the head/helmet and likely type of impact. It's basically styrene with bigger and smaller bubbles to create different densities. It's not new, AGV have used it in their road helmets for a long time.

So in a nutshell: Brain injury is caused by your brain impacting against your skull. Shock absorption is the answer. Therefore get a helmet with quality construction, a multi-block/density design and a strong but fairly soft shell. Composites like fiberglass/kevlar/carbon have proven effective. And don't forget correct fit. Fit is key.

DH helmets are fine... except that when I rode head first into a tree my THE one wasn't crumpled, cracked, dented or broken in any way and yet I compressed my spine enough to break my back in for places. I have always thought MX helmets were too over engineered for DH so I've gotten a D3. I don't care if it's expensive. 10$ helmet 10$ head... Never getting a DH helmet again after what happened to me. And now that this post confirmed what I already knew I'll never get an MX lid either. D3 all the way